To give everyone some perspective on the incomplete nature of the underlying science I wish to link this announcement of a study that has finally recognized how the different protein subunits in a normal mitochondrial respiratory supercomplex fit together. The complete, but less intelligible, paper is here. Up until this time we were all in considerable darkness about what was going on in these vital organelles of every living cell. Even when we knew all the pieces, what we had was like a bag of lego pieces, not a structure. We still don't know a great deal about how this relates to function, although there are now some very interesting conjectures to consider. The human mitochondrial genome itself has only 37 genes, and only 13 of these code for proteins. A mitochondrion contains about 3,000 different proteins, most of which are coded in nuclear DNA on chromosomes. If we are just now figuring out how the pieces literally vital for respiration fit together in healthy mitochondria, you can form your own estimate of how far we are from completely understanding mitochondrial diseases.